Planar

From Late Latin planarius ("relating to a plane"), from planum ("plane").

Full definition of planar

Of or pertaining to a plane.A planar projection of a three-dimensional object is its projection onto a plane.
Flat, two-dimensional.
(graph theory, of a graph) Able to be embedded in the plane with no edges intersecting.A complete graph with more than four nodes is never planar.
(transistor chip, semiconductor devices) Having a flat profile, not etched into a mesa.